WASHINGTON — Scarlett Johansson politely declined an invitation to speak to the 14,000 people gathering here Sunday for the annual meeting of the American Israel Public Affairs Committee, or Aipac, as the nation’s most powerful pro-Israel lobbying group is known.

She has to be in Paris to collect an honorary César film award, her publicist said, and then she is promoting two new movies, “Under the Skin” and “Captain America: The Winter Soldier.” Aipac’s members will have to settle for Treasury Secretary Jacob J. Lew as a Sunday headliner.

But the Hollywood actress will be at Aipac in spirit. After refusing to give up an endorsement deal with SodaStream, an Israeli company that has a factory in a Jewish settlement in the Israeli-occupied West Bank, Ms. Johansson has become a hero to pro-Israel activists — a living, breathing, deeply glamorous repudiation of the movement to boycott Israel.

In speeches by Prime Minister Benjamin Netanyahu and other officials next week, Aipac plans to pound the drums about what it regards as the pernicious motives of the anti-Israel campaign, known formally as the boycott, divestment and sanctions, or B.D.S., movement.

The movement, which began in the Palestinian territories in 2005, demands that Israel end its 1967 occupation of the West Bank, give full rights and equality to Palestinian Arab citizens, and, most controversially, allow Palestinians to return to places from which they were displaced in 1948 after the founding of the state of Israel.

Aipac’s response is to push for expanded engagement with Israel, and to urge Congress to battle against Palestinian efforts to exclude Israel from international organizations. “Our message is one of inclusion,” said a senior Aipac official who spoke on the condition of anonymity, in keeping with the group’s practice.

At one level, giving the boycott movement such attention seems odd. While it has gained some traction in Europe, where a Dutch pension fund recently cut ties to Israeli banks that do business with Jewish settlements, it remains largely a non starter in the United States.

When the American Studies Association voted in December to boycott Israeli universities because of Israel’s treatment of the Palestinians, it was widely derided by other American scholarly groups.

IBM, Cisco and EMC are among American technology companies that have recently announced investments in Israel. The country attracted $10.5 billion in foreign direct investment in the first three quarters of 2013, compared with $9.5 billion for all of 2012.

But a recent warning by Secretary of State John Kerry, and Mr. Netanyahu’s indignant response, have made B.D.S. look like a more imminent threat than it is. Mr. Kerry, speaking at a security conference in Munich, said that if the latest round of peace talks between the Israelis and the Palestinians collapsed, Israel could face deepening isolation.

“For Israel, there’s an increasing delegitimization campaign that has been building up,” Mr. Kerry said. “People are very sensitive to it. There are talk of boycotts and other kinds of things.”

Mr. Kerry came under fierce fire from Israeli officials for his remarks. One said that Israel would never negotiate “with a gun at its head.” Mr. Netanyahu, while not criticizing Mr. Kerry directly, said, “Attempts to impose a boycott on the state of Israel are immoral and unjust.”

Omar Barghouti, a Palestinian human rights activist and a B.D.S. leader, wrote recently in an Op-Ed article in The New York Times that the Israeli government’s strident response “reveals its heightened anxiety at the movement’s recent spread into the mainstream.”

By all accounts, though, Mr. Kerry meant his warning in a descriptive rather than a prescriptive manner. He will have a chance to clear up any lingering confusion when he speaks to Aipac on Monday evening. Either way, it will keep B.D.S. on the group’s agenda.

There is another reason for Aipac to keep the boycott movement front and center: It is a reliable way to fire up its rank and file. And that could come in handy in a year when the group finds itself uncharacteristically on its heels on its biggest legislative priority, Iran.

Its campaign for new sanctions against Tehran has stalled in the Senate, where the Democratic leadership has so far acquiesced to intense pressure from the White House not to act while the United States and its partners are in delicate talks with Iran over its nuclear program.

Aipac insists it still favors the passage of a bill. In an Op-Ed article in The Times last week, the group’s two top officials, Michael Kassen and Lee Rosenberg, wrote that diplomacy, backed by further sanctions, was “the best chance to avoid military conflict with Iran.”

But the two men said they concurred with the decision of one of the bill’s co-sponsors, Senator Robert Menendez, Democrat of New Jersey, to delay a vote. The Senate’s Democratic leader, Harry Reid of Nevada, cited that concession this week to avoid attaching Iran sanctions to another bill.

Compared with Aipac’s mixed signals on Iran, there is a bracing clarity in fighting the boycott movement. B.D.S. is about delegitimizing Israel, in the view of pro-Israel activists. It is not just anti-Israeli, they say, but antithetical to a peace treaty with the Palestinians.

They point, in particular, to the movement’s demand for a right of return for dispossessed Palestinians — which, if carried out, would effectively end the viability of a Jewish state, in the view of Middle East experts.

“It’s not a real threat to Israel, but it’s a threat to the peace process,” said Josh Block, a former Aipac spokesman who is now the chief executive of the Israel Project. “We live in a dangerous world, and if you ignore them and don’t call them out, you give them legitimacy.”

Mr. Block’s nonprofit group has turned Ms. Johansson into a poster girl for the pro-Israel movement. It started an online campaign, after she appeared in a commercial for SodaStream during the Super Bowl, to thank her for being “our Super Bowl M.V.P.” — complete with a sultry, retouched photograph of the actress, a peace tattoo stamped on her bare shoulder.

It is tough to see how either Mr. Kerry or Mr. Lew is going to be able to top that at the Aipac meeting next week.